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采用摩擦学中的自锁概念提出了确定弱面破坏的模型和分析方法,物理概念简单明确。采用自锁概念分析二维弱面破坏与采用莫尔–库仑定律得到的结果一致。三维弱面模型在弱面与中间主应力平行和中间主应力等于最小主应力两种情况下,可退化为二维弱面问题。研究结果表明:主应力、弱面力学参数对空间弱面破坏角度范围的影响显著,包括破坏角度范围大小和形态变化两个方面。随着弱面力学参数的增加,空间弱面破坏角度范围有变小的趋势,当弱面力学参数达到一定数值后,岩体中的弱面倾角和走向取任意值,岩体均不会发生弱面破坏。随着中间主应力和最小主应力的增加,空间弱面破坏角度范围具有变小的趋势。通过建立局部坐标系,得到了裂缝性地层井壁发生失稳的弱面角度随井底压力变化的规律。
Adopting the concept of self-locking in tribology, a model and analysis method for determining the damage of the weak surface are proposed. The physical concept is simple and clear. Using the concept of self-locking analysis of two-dimensional weak surface damage and the use of the results of the use of the Mole-Coulomb law is consistent. The three-dimensional weak face model can degenerate into the two-dimensional weak face problem under the condition that the weak face is parallel to the middle main stress and the middle main stress is equal to the minimum principal stress. The results show that the mechanical parameters of the principal stress and the weak plane have significant effects on the failure angle of the weak plane, including the scope of the damage angle and the morphological changes. With the increase of the mechanical parameters of the weak surface, the failure angle of the spatial weak surface tends to decrease. When the mechanical parameters of the weak surface reach a certain value, the inclination and the direction of the weak surface in the rock mass take arbitrary values, and the rock mass will not occur Weak face damage. With the increase of the intermediate principal stress and the minimum principal stress, the range of the failure angle of the weakening of the space tends to decrease. Through the establishment of local coordinate system, the law of the weak surface angle of wellbore in fractured strata varies with the bottom hole pressure.